As your iTunes Library continues to grow, the time may come when it outgrows the available space left on your hard drive. When that happens, a common solution is to move your library to another (larger or more empty) drive. Doing this is not difficult.

However, as iTunes has a number of similar-sounding options and installs a number of similar-sounding iTunes-related files on your drive, it may not be self-evident how to go about moving your music library. What makes the task potentially treacherous is that a wrong move can leave your music files in a state where iTunes is no longer able to find or play them.

Here’s how to avoid this:

Move only the iTunes Media folder; leave the rest alone

By default, your iTunes Library files, together with an assortment of other iTunes-related files, are located in the Music -> iTunes folder of your Home directory. Within this iTunes folder is a folder named iTunes Media. This is where all the gigabytes of your audio and video files are stored.

(Note: If you have an older version of iTunes or have not updated the folder organization, the relevant folder may be named iTunes Music instead of iTunes Media. Also, if you deselected the default option to copy files imported to iTunes, your media files may be scattered anywhere on your drive, not just in the iTunes Media folder. For simplicity, I am assuming that’s not the case here.)

Look before you leap

You may think the first thing you should do is copy your iTunes Media folder to your desired new location. You would be wrong.

Actually, this might work if you were moving, rather than copying, the folder to another location on the same drive partition. In a support article, Apple explains how to move an iTunes Music/Media folder so as to make it shareable. In brief, it says:

Move the iTunes Music/Media folder to the desired new location (such as to the Shared user folder);

From the iTunes menu, choose Preferences and navigate to Advanced;

Click the Change button for “iTunes Media folder location” and enter the new location of the folder.

However, for relocating your Library to a new drive/partition, you will be copying the iTunes Media folder. If you attempted the above procedure, and then deleted the original supposedly-no-longer-needed iTunes Media folder, you will wind up in trouble. iTunes will continue to list all your files. But when you click to play any of them, you will get a message that the file “could not be found.”

This happens because changing the location listed in Advanced in this case only affects where “new songs and other items you import” are stored. For your existing media, iTunes still expects them to be in the now-deleted original location — which is why iTunes can’t find them.

When I tested this out, I tried several potential fixes, short of copying the folder back to its original location and starting over. None of them worked. For example, I held down the Option key when launching iTunes. This brought up a dialog from which you can select to choose a new Library. Doing so had no effect.

How to do it right

Before you move anything, list the intended new location in the Advanced section of iTunes Preferences;

From the File menu of iTunes, choose Library -> Organize Library;

From the dialog that appears, select to “Consolidate files.” Doing this will copy all the files to the new location. When complete, you can delete the original iTunes Media folder. Everything should now work as expected.